Legume α-Galactosidases Which Have Hemagglutinin Properties

Abstract

Four legume species (four genera) were examined and found to contain hemagglutinins with properties similar to those which we have previously described for the enzymnic hemagglutinin in Vigna radiata. Examination of extracts by gel filtration and ion exchange chromatography showed that an a-galactosidase activity exactly co-purified with a hemagglutinin activity in each of the four species. The a-galactosidase activities in the four species were virtually identical to each other with respect to substrate and inhibitor specificity as well as kinetic behavior. Additionally the hemagglutnin activities in all four species displayed very similar carbohydrate specificities. The inhibitor specificities displayed by the enzymes and the hemagglutinins were qualitatively and quantitatively very nearly identical to each other. The remarkable similarities of these proteins, both to each other and to the previously described Vigna enzymic hemagglutinin, suggest that each of these plants may contain a homologue from a specific class of enzymic hemagglutinin.In a previous report we described an a-galactosidase from Vigna radiata which possessed hemagglutinin properties (4). The Vigna hemagglutinin displayed a unique property which we refer to as "clot-dissolving activity." Apparently, under the appropriate conditions, this protein is capable of enzymically altering those erythrocyte receptors with which it interacts, resulting in a dissolution ofcell aggregates. The disaggregated erythrocytes are permanently altered and are no longer agglutinable by Vigna hemagglutinin (although they remain agglutinable by many other legume lectins). Clot-dissolving activity is readily observed, even with crude extracts, as a disappearance (dissolution) of erythrocyte aggregates at a rate which is directly proportional to the concentration of extract used. That is, with very concentrated extracts, agglutination is rapid and complete but very quick (minutes) to disappear; with dilute extracts, full agglutination develops more slowly and then disappears only after prolonged (hours) incubation.Due to our general interest in hemagglutinins, we wondered if legume species other than Vigna contained similar clot-dissolving agglutinins. We, therefore, surveyed a variety of legume seed extracts for hemagglutinin and a-galactosidase activities and, in those cases where agglutination was seen, we carefully looked to see if any clot dissolution occurred. We readily detected clotdissolving activity in several species, including two which contained previously well characterized non-clot-dissolving hemagglutinins.In this report we describe some general properties of extracts from four different legume species (four genera) each of which contains a clot-dissolving hemagglutinin. Our results suggest that all four species contain a-galactosidase-hemagglutinins very similar to that isolated from V. radiata.

An α-Galactosidase with Hemagglutinin Properties from Soybean Seeds

“…The proteins are separable, apparently immunologically unrelated, and display distinct carbohydrate specificities. Soybean seeds, therefore, possess two types of hemagglutinin, which provides further support for the conclusion that the a-galactosidase-hemagglutinins and N-acetylgalactosamine-specific lectins are members ofdistinct classes of proteins (4).…”

“…3). The a- galactosidase specific hemagglutinin activity in soybeans also displays 'clot-dissolving activity,' a phenomenon which has been described in detail elsewhere (4,5).…”

“…The a-galactosidase-hemagglutinin in soybean seeds is clearly distinct from soybean agglutinin, the N-acetylgalactosamine specific lectin which is also present in soybean seeds (4,7). The proteins are separable, apparently immunologically unrelated, and display distinct carbohydrate specificities.…”

“…Previously, we reported that partially purified a-galactosidase preparations from several legumes, including soybeans, appeared to display associated hemagglutinin properties (4,5). Only in mung beans, however, has it been conclusively demonstrated that both enzyme and hemagglutinin activities are associated with a single protein species (2,5).…”

Isolation, characterization and production of a new recombinant lectin protein from leguminous plants

“…Leguminous seeds are a rich source of lectins, many of which possess homologous segments of amino acids and, hence, may have an evolutionary relationship [11]. Few examples of enzymes possessing lectin activity have been reported but cumannosidase from Phaseolus vulgaris seeds [21] and α-galactosidases obtained from several species of leguminous seeds [6] have been shown to be lectins. Lectin is very important for human health, so the studies aimed to purify and intensify the efficiency of new lectin specially derived from legumes.…”